Chromium is a strategic metal in the United States because of the nearly 100% import dependence and wide variety of important uses. Among the most critical uses for chromium is providing high temperature and oxidation resistance in both cobalt and nickel based superalloys. In order to be utilized in this application, the chromium must be of high purity. Other common uses for the metal for example in stainless steel have less stringent purity requirements.
Annually, millions of pounds of superalloy materials are removed from service and are downgraded as scrap. Much of the scrap superalloy is exported from the United States or used domestically for steel production. The value of the scrap is many times less than the value of new alloy and in some cases is less than the value of the constituent metals. Therefore this practice represents a large dollar loss as well as a loss of strategic metals from the US economy.
The recycle of superalloy materials other than by direct remelting has been economically unfeasible up to this time. In part this has been due to the lack of technology for dissolution of large amounts of material at reasonable rates. In addition, since most of the chemistry for the production of chromium metal is based on chromite ore as a starting material, separation methods to remove elements found in used superalloys but which do not naturally occur in chromite have not been fully developed.